1. Field of the Invention
The present invention relates to a collator for accommodating record media ejected from a laser beam printer, a copying machine or the like, and more particularly to a collator which can select any storage pocket.
2. Description of the Prior Art
In a prior art laser beam printer or high speed copying machine, a stacker is used to stack record media (hereinafter referred to as transfer papers) to accommodate the ejected transfer papers. Such a stacker is simple in structure, is inexpensive and allows a large volume of stack, but in order to sort the stack, papers having special marks printed thereon must be placed between the papers to allow the alternation of the manner of stacking. When a plurality of sets of copies of the same text are to be prepared, the collation is difficult to attain. In order to avoid the collation, output to the laser beam printer may be repetitively applied from the beginning to the end by the number of times equal to the desired number of sets of copies. However, it takes a long waiting time and leads to a reduction of throughput (the number of copies produced in a given time period) of the high speed terminal such as the laser beam printer.
In a sorter usually used in the copying machine, copies can be produced within a limit of a maximum number of copies which can be stacked in one bin and within a limit of the number of bins in the sorter. For example, when five sets of copies are to be produced with a 20-bin sorter, five bins are used and the remaining fifteen bins are not used. If a capacity of each bin is 50 copies, copies can be produced for a set of up to 50 pages. However, in the high speed machine such as laser beam printer or high speed copying machine, the bins are filled in a short time and an operator has to frequently take out the copies. This is troublesome to the operator. Furthermore, in the copying machine, when a page of the text is to be changed to a next page, the text page must be exchanged. Accordingly, it cannot occur that a first copy for the next text page is produced immediately after the last copy of the current text page. Therefore, it is possible for a switching mechanism of the sorter bins to select a first bin during that period to allow the accommodation of the copies in the first bin. In the laser beam printer, however, since it is possible to output page information serially, when five sets of copies, for example, are to be produced, a first copy for the page eleven is produced immediately after the production of the fifth copy for the page ten so that the first copy for the page eleven must be accommodated in the first bin before the fifth copy for the page ten enters the fifth bin. In a conventional sorter, in order to prevent such a phenomenon from occurring, the copying operation for the next page is suppressed until all of the copies for the currently copied page have been accommodated in the bin. Thus, because of such nature of the sorter, the waiting time of the laser beam printer, which allows the sequential output in nature, increases which leads to substantial reduction of the throughput.